The interior of a typical automotive vehicle has an instrument panel which faces a driver of the vehicle and a front seat passenger. A head unit, sometimes referred to as a radio head or radio head unit, is typically disposed centrally in the instrument panel for viewing, and access, by both a driver and a passenger. A radio head unit provides various functional capabilities.
A typical radio head unit comprises an electronic display screen and various inputs such as control switches for controlling various functions of the radio head unit and other devices and/or functions which are fully or partially controlled by or through the radio head unit. Additional control switches may be present in the instrument panel outside the radio head unit and electrically connected with the radio head unit for controlling certain functions within the radio head unit and/or functions which are remote from, but controlled, through the radio head unit.
The vehicle has a radio antenna for sending and receiving radio transmissions. The radio antenna is connected to a radio receiver in the radio head unit. The radio receiver comprises circuitry for converting received radio transmissions into audio signals. Amplification circuitry amplifies the audio signals which are then input to an audio system having speakers which convert the amplified audio signals into audio content which can be heard by vehicle occupants.
Control switches, whether in the radio head unit or elsewhere in a vehicle, such as on a steering wheel, can select audio signals from in-vehicle sources, such as CD and DVD players for example, to be input to the amplification circuitry and consequently be heard by vehicle occupants instead of broadcast radio. Such other sources may be built into the radio head unit or may be self-contained auxiliary devices which plug into or have wireless communication with the radio head unit.
The control switches perform various functions such as selecting the audio source, setting audio quality and volume, selecting specific content from a selected source, selecting a particular broadcast radio band, and selecting a particular radio station within a band.
The antenna may be designed with capability for receiving not only radio signals in AM, FM and other broadcast radio bands, such as satellite radio. The antenna may also be designed to receive signals from satellites of the Global Positioning System (GPS) for use in navigation.